[sesutton]

Is it possible to deactivate old IDs?

[Zak]

It is possible to set the ID manually. Titanium Backup does this, for example.

[paulie_a]

Previously they expired after 18-24 months, I am not sure if that is still true

It was annoying to have old dead devices still on my account with no way to remove them

[kuschku]

No – it’s 100 times of installing ROMs per lifetime, then you’re EOL.

[rorosaurus]

Wow, if that's true, that changes the whole tone of this. Hopefully this is just a temporary oversight, and Google allows the opportunity to delete and reuse these 100 slots.

[ocdtrekkie]

I suspect if they were intended to be "reusable slots", it would be a drastically smaller number, like... five.

[nstart]

Which is actually fine. 5 is restrictive but 15 is just fine.