Free products are mostly welcomed, however, using pirated software might seput your computer at risk.

Set is unnatural here.

Some viruses might havbe embedded into the software, damaging your computer.

Therefore, I suggest using legal, official software, t. This can eitherboth supports the developers or makeand keeps our computers in good condition.

Using legal software does both of these things, so using either is incorrect. Either should be used when either one or both could be true.

Free products are mostly welcomed,; however, using pirated software might seput your computer at risk.

Some viruses might have been embedded into the software, which can damaginge your computer.

i don't think your version is necessarily incorrect grammar, but i feel like it sounds slightly more natural with these changes.

Therefore, I suggest using legal official software,; this can either support the developers or makeand also keep our computers in good condition.

I feel like either a semicolon or a period can be used here to better separate the clauses, I chose a semicolon. Also I changed the "either/or" because both of these statements can be true at the same time, as using legal official software can both support developers and keep our computers in good condition

Free products are mostusually welcomed, however, using pirated software might seput your computer at risk.

"Mostly welcome" feels more natural than "mostly welcomed" to me, but I think most natural would be "usually welcome". Welcome can be both an adjective and a verb (Or a noun as well!) but I use it as an adjective in this sort of sentence.

I would also say something is "put at risk" rather than "set at risk".

Some viruses might have been embedded into the software, which could damaginge your computer.

Just some minor changes.
To me "have been embedded" makes it sound like someone embedded the viruses into the software, rather than the viruses embedding themselves.

"damaging your computer" is fine, but to be REALLY picky, it makes it sound like the computer was already damaged just by the viruses being embedded in the software. Rather, embedded viruses are just a threat, they don't damage anything yet just by being embedded. Only once the program has run would they damage the computer, so "could damage" is slightly more accurate. But this could be a mistake a native speaker would make when speaking casually.

Therefore, I suggest using legal official software,; this can eitherboth support the developers orand make our computers stay in good condition.

" ; " is used to separate two clauses that could be their own sentences. "Therefore I suggest using legal software" and "this can both..." could both be their own standalone sentences, so I suggest using a ";"!

Both of these things are true at the same time, supporting developers AND protecting computers, so I think "both" makes more sense than "either".
And this one is REALLY picky, but it technically doesn't make the computers good, just makes sure they stay safe, so I made the distinction with "stay in good condition". But again, this is more a technical detail and something a native speaker could get tripped up by.

Free products are mostly welcomed,; however, using pirated software might set your computer at risk.

Very minor but "however" cannot connect 2 sentences together with commas. Can also be "...welcomed. However, using..."

Some viruses might havbe embedded into the software, damaging your computer.

I think "have" is okay, but I think "be" is more natural.

Therefore, I suggest using legal official software, t. This can eitherboth support the developers or makeand keep our computers in good condition.

Your sentence was grammatically correct (other than the period), but I changed it to make logically more sense.