Are there any restrictions in activating pro plan?

Yes — the Pro plan is tied to seat/workstation limits, and one license can be used for one device plus one spare device only. For Genymotion Desktop Business/Pro, the plan is per user and workstation, and exceeding the allowed activations can trigger the “maximum number of workstations” error. Find your perfect Genymotion plan I get the error: "You have activated the maximum number of workstations allowed by your license"

If you reinstall your OS or change computers, that can count as a new activation. In that case, the activation-reset request is available in the help center article above.